Since downsizing and weight saving of electronic devices have been advancing, secondary batteries whose energy density is high have been desired for their power source. A secondary battery is one that takes out chemical energy, which the positive-electrode active material and negative-electrode active material possess, to the outside as electric energy by means of chemical reaction through electrolyte. In such secondary batteries, lithium-ion secondary batteries are secondary batteries, which possess a higher energy density, among those that have been put in practical use.
For lithium-ion secondary battery, lithium-containing metallic composite oxides, such as lithium-cobalt composite oxides, have been used mainly as an active material for the positive electrode. As for an active material for the negative electrode, carbonaceous materials, which have a multi-layered structure that enables the insertion of lithium ions between the layers (i.e., the formation of lithium intercalation complex) and the discharge of lithium ions out from between the layers, have been used mainly.
The electrode plates for positive electrode and negative electrode are made in the following manner: these active materials, a binder resin and a conductive additive are dispersed in a solvent to make a slurry, respectively; then the resulting slurries are applied onto opposite faces of a metallic foil, namely, a current collector; and then the solvent is dry removed to form mixture-agent layers; and thereafter the resulting mixture-agent layers and current collector are compression molded with a roller pressing machine.
Moreover, as the negative-electrode active material for lithium-ion secondary battery, the development of next-generation negative-electrode active materials, which possess a charge/discharge capacity that greatly exceeds the theoretical capacity of carbonaceous material, has been advanced recently. For example, materials that include a metal, such as Si or Sn, which is capable of alloying with lithium, are regarded prospective.
In the case of using Si or Sn, and so forth, for an active material, since these materials exhibit a great volumetric change that is accompanied by the occlusion/release of Li at the time of charging/discharging, it is difficult to maintain the bonded state to current collector satisfactorily. Moreover, these materials exhibit a very large rate of volumetric change that is accompanied by the insertion and elimination of lithium, and repeat expansion and contraction due to charging/discharging cycle. Since their active-material particles have been pulverized finely, or have come to be detached, by means of the expansion and contraction of the active material, these materials are associated with such a drawback that the cyclability degradation is great considerably.
Consequently, various combinations of binder resins and active materials have been investigated in order to make the active materials less likely to come off or fall down.
In Patent Literature No. 1, an electrode for secondary battery is proposed, electrode which uses an alkoxy group-containing resin as a binder resin.    Patent Literature No. 1: Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2009-43,678